Police had filed for a search warrant of Barnes' Facebook account by 3 p.m. the day after the April 11 murders. (Catherine Green/Neon Tommy)

Swift connections made in the fatal shooting of two USC graduate students April 11 led Los Angeles Police Department detectives to zero in on a suspect within 24 hours, according to court documents.

The files show that within hours of Wu Ying and Qu Ming’s murders, police had picked out 20-year-old Bryan Barnes as a primary suspect. A key witness identified him in an earlier shooting tied to the same weapon used to kill the two international students.

By 3 p.m., April 12, Detective Erbie Phillips had gone to the courthouse to obtain a search warrant for Barnes’ Facebook account. Over the next several weeks, police closed in on Barnes and his alleged accomplice, 19-year-old Javier Bolden, through surveillance.

Combing a waterlogged crime scene on South Raymond Avenue, about a mile from the USC campus, in the early hours of April 11, police collected what evidence they could—most notably several shell casings from a 9mm semi-automatic handgun.

“Even though it was raining heavily, we were able to still salvage that evidence and send it out for forensic analysis,” Deputy Chief Pat Gannon of the LAPD’s Southwest Division said in a May 19 interview. By 6 p.m. that day, detectives had matched the casings to those found at two previous crime scenes, a Feb. 12 shooting and another on Dec. 3, 2011, when 20-year-old Timothy Hall was shot and wounded at a South L.A. party.

A late-night party on Feb. 12 also ended in violence when an unidentified shooter opened fire, hitting a young woman, Zanae Flowers, in the calf and 21-year-old Deionce Davance in the stomach and head, according to case files. The felony complaint report goes on to say officers found Davance lying face-up on the ground, motionless and covered in blood. He and Flowers were taken to the hospital where Davance fell into a coma. When he awoke, the young man was paralyzed.

“Work had been done on those cases,” Gannon said Sunday. “But [the detectives] hadn’t gotten to the point where they could positively identify these guys as having been involved. You know, they do unfortunately have a lot of shooting cases. They were working towards it but just hadn’t gotten there yet.” Gannon said police had more leads in the February and December shootings, including witness accounts. When Ying and Ming were gunned down in April, detectives thought to call again on one witness in particular.

Phillips and an LAPD sergeant met with the witness at 9:30 p.m., nearly 20 hours after the USC students were killed. Details of that interview are recounted in a sworn statement that persuaded Judge Kelvin Filer on April 12 to issue the warrant for Barnes’ Facebook account. Under the header “Investigative information positively identifying the perpetrator as the suspect,” Phillips reported, “During initial interview, [the witness] mentioned to Detectives that he could positively identify the shooter in this case. [The witness] had researched information that he received from partygoers and located a man by the name of [Bryan Barnes].”

According to the affidavit, the witness said after talking to others who had been at the party that night, he had found the shooter on Facebook. When detectives pulled up the social networking site on a department computer, the witness quickly navigated to Barnes’ profile, pointed at the screen and said, “That’s him! That’s the guy that shot [one of the Feb. 12 victims].” Profile photos viewed on that first visit showed Barnes and his friend Bolden both flashing gang signs. The page also displayed a logo linked to the Black P Stones gang.

“That was really the first break we had,” Gannon said. As students wrapped up an on-campus candlelight vigil for Ying and Ming the night of the shooting, police had already tracked down a firm lead for a suspected killer.

The Facebook search warrant sought basics about the subscriber—Barnes’ gender and birthday, his location details and various IP addresses. Police requested access to his stored files, everything from his mini-feed and status updates to private messages with users on his friend list. Information yielded by the online warrant linked Barnes and Bolden, who appeared in many of the primary suspect’s personal photos, to the party crew No RespectInc.

Detectives began to paint a fuller picture of their suspects, one of fringe gang affiliation and violent arrogance. Using surveillance and other tracking methods over the next several weeks, they narrowed in on their suspects. In that time, additional search warrants were secured for three addresses—one in Lancaster, another in Palmdale and one for a bright blue house on 91st Street in South L.A.

On May 18, a quiet Friday afternoon, police stormed the apartment to take Barnes into custody, arresting Bolden at a social worker’s home in Palmdale three hours later. Those search warrants have been sealed by a judge. The felony complaint filed May 22 by the D.A.’s office includes five counts against Barnes: two counts of murder in the shootings of Ying and Ming; two counts of attempted murder in the December shooting of Timothy Hall and the February shooting of Deionce Davance, including the allegation Barnes inflicted “great bodily injury”; and one count of assault with a semi-automatic firearm in the shooting of Zanae Flowers.

Bolden faces three of the same charges—both counts of murder in the April shootings as well as the attempted murder Dec. 3. Their arraignment was postponed until June 25 to allow attorneys time to prepare their case.

Among the questions that remain unanswered as Barnes and Bolden await their day in court: When did police make the connection between the February and December shootings? If early enough, how aggressively did they try to find the young men terrorizing parties in South L.A.?

And most haunting, would Ying and Ming still be alive today if the earlier cases had been as intensely investigated as the double homicides?

On Sunday, Deputy Chief Gannon reiterated the D.A.’s request that the LAPD keep details of the case under wraps. But he also addressed in general terms the level of investigative work involved in high-profile homicides cases compared with other shootings.

“Every crime that we get in the city is important to us, but you’re right,” he said. “The amount of resources we’ve placed on those individual crimes changes along the way depending on volume and everything that we have.”

Gannon attributed the intensified efforts to solve the USC student killings to the nature of the crime.

“When it comes to homicide, that is the one crime that I try to put as much emphasis and effort as I possibly can into it,” he said. “I try to deploy as many people as I possibly can to solve every single one of those crimes. That’s my goal. Am I successful with it? No, I’m not.”

Despite the LAPD’s quick work detailed in the court files, Gannon expressed some regret regarding the pace of the two earlier investigations in February and last December. “In this particular case, yes, it might have been nice to have linked all these cases together with these individuals and gotten it solved,” he said. “Maybe the murders would never have occurred.”